Glycemic control monitoring using implantable medical device

Abstract

An apparatus for monitoring a patient's blood glucose level. The apparatus includes an implantable medical device having a controller and an implantable heart sounds sensor configured to transmit signals to the controller of the implantable medical device. The controller is configured to determine if a patient is hypoglycemic or hyperglycemic based on the signals from the heart sounds sensor. A method is also disclosed that includes sensing the patient's heart sounds, determining the amplitude of the S2 heart sound, determining the length of the interval from the S1 heart sound to the S2 max heart sound, determining the length of the interval from the S1 heart sound to the S2 end heart sound, and determining the patient's blood glucose status based on the patient's heart sounds.

1. An apparatus for monitoring a patient's blood glucose level, the apparatus comprising:
 (i) an implantable medical device having a controller; 
 (ii) an implantable heart sounds sensor configured to transmit signals to the controller of the implantable medical device; and 
 (iii) wherein the controller is configured to determine if a patient is hypoglycemic or hyperglycemic based on the signals from the heart sounds sensor, wherein the controller is configured to detect the amplitude of an S2 heart sound from the signals from the heart sounds sensor, determine the time interval between an S1 heart sound and the time of the maximum amplitude of the S2 heart sound (S2 max ), determine the time interval between the S1 heart sound and an end of the S2 heart sound (S2 end ), 
 
       where the controller stores baseline data derived from a signal from the heart sounds sensor and then compares signals later received from the heart sounds sensor to the baseline data to determine if a patient is hypoglycemic or hyperglycemic; and 
       wherein the controller determines that the patient is hypoglycemic if the amplitude of the S2 heart sound deviates by a predetermined threshold from a baseline, and if both the time interval from S1 to S2 max  and from S1 to S2 end  lengthens relative to the baseline by a predetermined threshold. 
     
     
       2. The apparatus of  claim 1 , where the controller determines that the patient is hyperglycemic if the amplitude of the S2 heart sound deviates by a predetermined threshold from baseline, and if both the time interval from S1 to S2 max  and from S1 to S2 end  do not change by more than a predetermined threshold from the baseline. 
     
     
       3. The apparatus of  claim 1 , where the implantable medical device is a cardiac rhythm management (CRM) device such as an implantable pacemaker, implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy (CRT) device. 
     
     
       4. The apparatus of  claim 1 , where the implantable medical device further includes a transmitter for transmitting telemetric signals to a non-implantable device, where the implantable medical device transmits telemetric signals to the non-implantable device when the controller determines that the patient is hypoglycemic or hyperglycemic, and where the non-implantable device is configured to provide a message that is perceptible to the patient indicative of whether the patient is hypoglycemic or hyperglycemic. 
     
     
       5. The apparatus of  claim 1 , further comprising an implantable drug pump in communication with the controller, and where the implantable drug pump is configured to deliver a drug dosage to a patient in response to a determination in the controller that the patient is hypoglycemic or hyperglycemic. 
     
     
       6. The apparatus of  claim 1 , further comprising a body motion sensor configured to transmit signals to the controller, and where the controller is further configured to determine if a patient is hypoglycemic or hyperglycemic when the signal from the body motion sensor is within a predefined range. 
     
     
       7. The apparatus of  claim 6 , where the predefined range corresponds to the patient being generally sedentary. 
     
     
       8. The apparatus of  claim 1 , further comprising a body posture sensor configured to transmit signals to the controller, and where the controller is further configured to determine if a patient is hypoglycemic or hyperglycemic when the signal from the body posture sensor is within a predefined range. 
     
     
       9. The apparatus of  claim 8 , where the predefined range corresponds to a patient being in a generally horizontal posture. 
     
     
       10. The apparatus of  claim 1 , where the implantable heart sounds sensor is an accelerometer. 
     
     
       11. An apparatus for monitoring a patient's blood glucose level, the apparatus comprising:
 (i) an implantable medical device having a controller; 
 (ii) an implantable heart sounds sensor configured to transmit signals to the controller of the implantable medical device; and 
 (iii) wherein the controller is configured to determine if a patient is hypoglycemic or hyperglycemic based on the signals from the heart sounds sensor, wherein the controller is configured to detect the amplitude of an S2 heart sound from the signals from the heart sounds sensor, determine the time interval between an S1 heart sound and the time of the maximum amplitude of the S2 heart sound (S2 max ), determine the time interval between the S1 heart sound and an end of the S2 heart sound (S2 end ), 
 
       where the controller stores baseline data derived from a signal from the heart sounds sensor and then compares signals later received from the heart sounds sensor to the baseline data to determine if a patient is hypoglycemic or hyperglycemic; and 
       where the controller determines that the patient is hyperglycemic if the amplitude of the S2 heart sound deviates by a predetermined threshold from baseline, and if both the time interval from S1 to S2 max  and from S1 to S2 end  do not change by more than a predetermined threshold from the baseline. 
     
     
       12. The apparatus of  claim 11 , where the implantable medical device further includes a transmitter for transmitting telemetric signals to a non-implantable device, where the implantable medical device transmits telemetric signals to the non-implantable device when the controller determines that the patient is hypoglycemic or hyperglycemic, and where the non-implantable device is configured to provide a message that is perceptible to the patient indicative of whether the patient is hypoglycemic or hyperglycemic. 
     
     
       13. The apparatus of  claim 11 , where the implantable medical device is a cardiac rhythm management (CRM) device such as an implantable pacemaker, implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy (CRT) device. 
     
     
       14. The apparatus of  claim 11 , where the implantable medical device further includes a transmitter for transmitting telemetric signals to a non-implantable device. 
     
     
       15. The apparatus of  claim 11 , further comprising an implantable drug pump in communication with the controller, and where the implantable drug pump is configured to deliver a drug dosage to a patient in response to a determination in the controller that the patient is hypoglycemic or hyperglycemic. 
     
     
       16. The apparatus of  claim 11 , further comprising a body motion sensor configured to transmit signals to the controller, and where the controller is further configured to determine if a patient is hypoglycemic or hyperglycemic when the signal from the body motion sensor is within a predefined range. 
     
     
       17. The apparatus of  claim 16 , where the predefined range corresponds to the patient being generally sedentary. 
     
     
       18. The apparatus of  claim 11 , further comprising a body posture sensor configured to transmit signals to the controller, and where the controller is further configured to determine if a patient is hypoglycemic or hyperglycemic when the signal from the body posture sensor is within a predefined range. 
     
     
       19. The apparatus of  claim 18 , where the predefined range corresponds to a patient being in a generally horizontal posture. 
     
     
       20. The apparatus of  claim 11 , where the implantable heart sounds sensor is an accelerometer.